Kitchen Knives Set – Part 2: Making the Blades

There are multiple pictures, so I am putting the post below the fold. I have filmed most of these works, but if a video ever comes out, it won’t be this year. I am already getting a bit sidetracked by making this project more elaborate than I originally intended and by my desire to re-build and improve some of my tools. Whilst being hampered in my endeavors by cold weather and other, previously mentioned, things.

I am making these knives from 1,8 mm thick N690 steel, which is very thin. For hand-made I would say it is as thin as it gets, anything thinner I think would be nigh impossible to work by hand, it would be too easy to bend/break. And in anticipation of an inevitable future disaster, I have started to make two blades of each type.

All knife projects start first with scribing the rough outline of the knives on the steel blanks and center-punching markings for drilling the holes. I am not, however, marking the holes in the blade at this stage. This is because I am not intending to follow the templates exactly, I will adjust both the handles and the blades according to subjective feel in the hand, and the holes in the blade thus can only be punched and drilled when the blade outline is finite.

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In the confusion with filming, I have gone a bit overboard and I drilled one extra hole in the handle of one of the chef knives.

© Charly, all rights reserved. Click for full size.

In case you are wondering why I am drilling the huge holes at the heel of the blade, it is to save time and to improve the knife shape. I used to grind this part on the belt grinder, but it is very difficult to get a tight concave curve. And I have found out that pre-drilling that area with 14-20 mm holes makes my life later a lot easier.

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After the holes are drilled, I cut a very rough outline with an angle-grinder. And only after that I am going to the belt-grinder and grind the outline with an old and chewed-up 40 grit belt. I am using an old belt for this because the thin edge would quickly destroy a new one and for grinding away at the edge of soft steel a bit blunted belt suffices.

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With the outline of the blade mostly done, I could scribe, punch, and drill the holes in the big blades. And after that, I have scribed the lines for ricasso and for the primary bevel. However, on a blade this thin trying to establish sharp bevel would be a fool’s errand. These lines are only for rough orientation in order to get at least a somewhat symmetrical grind on the first belt to reduce warping.

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I went through the ceramic belts from 40 grit to 120 grit and the bevel line crept slowly all the way to the spine, leading to flat-ground and thin blades.

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The blades were packed in stainless steel foil with a piece of paper to prevent de-carburization during heat-treatment. As you can see, I have re-used some old foil from previous quenches because I am an old miser. And also because why use new disposable material when old disposable material is still good enough. You may notice there are seven blades. The seventh one is a blade that turned out to be insufficiently hardened in my last batch.

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For reasons that will be explained later, I went on to harden these blades with charcoal. Getting the required 1050 °C was easy, to heat only the blades and not the tangs not so much. As you can see I have again used my plate-quenching jig in combination with water.

All blades were hardened, none of them cracked in the quench and everything was hunky-dory so far. Except that the charcoal burned through the stainless steel foil so all of it was ruined and I have to buy a new one for the next batch. But that was bound to happen sooner or later anyway so whatever.

© Charly, all rights reserved. Click for full size.

And here are the blades just before they went into the baking oven for two two-hour tempering cycles at 180 °C. The greenish color is caused by a very thin layer of chromium oxide that has build up on the surface in the low-oxygen atmosphere under the stainless steel foil and ideally the whole blade would be green. Where the foil burned through – or where it was not present at all – the oxide layer is thicker and thus blue to black.

And this is where I was approximately two weeks ago, ready to enter the most time-consuming and boring part of the process – polishing. And this is where my original plans changed, leading to a significant slowing of my progress.



  1. says

    Thanks for the update. I find the process completely fascinating.

    Largely off-topic, when something’s measurement (usually thickness) ends up requiring fractional millimeters to state correctly, I find it fun to give the measurement in microns instead. (1800 microns for your blades.) I have so few occasions to use the units otherwise, and people get this weird subjective sense that microns only measure things human eyes can’t see because we rarely use them to measure visible things.

    Rather than simply having a hard time doing an arithmetic conversion of one unit to another, I find people often think that comparing microns to millimeters is like comparing apples to ideograms. Even I have that problem to some extent & I like the challenge to my own assumptions & perceptions.

  2. says

    @Marcus, Ice Swimmer got it right, those are the honing steels, I will write about those separately, probably I will make one post specifically about them once they are finished.

  3. voyager says

    I’m glad you’re making progress in terms of time managing your process. Every project you tackle seems to improve the way you do things, but I imagine that filming yourself would complicate that.

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